/**
 * Copyright (c) 2016 - 2020, Nordic Semiconductor ASA
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form, except as embedded into a Nordic
 *    Semiconductor ASA integrated circuit in a product or a software update for
 *    such product, must reproduce the above copyright notice, this list of
 *    conditions and the following disclaimer in the documentation and/or other
 *    materials provided with the distribution.
 *
 * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
 *    contributors may be used to endorse or promote products derived from this
 *    software without specific prior written permission.
 *
 * 4. This software, with or without modification, must only be used with a
 *    Nordic Semiconductor ASA integrated circuit.
 *
 * 5. Any software provided in binary form under this license must not be reverse
 *    engineered, decompiled, modified and/or disassembled.
 *
 * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
/** @file
 *
 * @defgroup ble_sdk_app_hids_keyboard_main main.c
 * @{
 * @ingroup ble_sdk_app_hids_keyboard
 * @brief HID Keyboard Sample Application main file.
 *
 * This file contains is the source code for a sample application using the HID, Battery and Device
 * Information Services for implementing a simple keyboard functionality.
 * Pressing Button 0 will send text 'hello' to the connected peer. On receiving output report,
 * it toggles the state of LED 2 on the mother board based on whether or not Caps Lock is on.
 * This application uses the @ref app_scheduler.
 *
 * Also it would accept pairing requests from any peer device.
 */

#include <stdint.h>
#include <string.h>
#include "nordic_common.h"
#include "nrf.h"
#include "nrf_assert.h"
#include "app_error.h"
#include "ble.h"
#include "ble_hci.h"
#include "ble_srv_common.h"
#include "ble_advertising.h"
#include "ble_advdata.h"
#include "ble_hids.h"
#include "ble_bas.h"
#include "ble_dis.h"
#include "ble_conn_params.h"
#include "sensorsim.h"
#include "bsp_btn_ble.h"
#include "app_scheduler.h"
#include "nrf_sdh.h"
#include "nrf_sdh_soc.h"
#include "nrf_sdh_ble.h"
#include "app_timer.h"
#include "fds.h"
#include "peer_manager.h"
#include "peer_manager_handler.h"
#include "ble_conn_state.h"
#include "nfc_ble_pair_lib.h"
#include "nrf_ble_gatt.h"
#include "nrf_ble_qwr.h"
#include "nrf_pwr_mgmt.h"
#include "nrf_ble_lesc.h"

#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"


#define DEVICE_NAME                      "Nordic_Keyboard"                              /**< Name of device. Will be included in the advertising data. */
#define MANUFACTURER_NAME                "NordicSemiconductor"                          /**< Manufacturer. Will be passed to Device Information Service. */

#define APP_BLE_OBSERVER_PRIO            3                                              /**< Application's BLE observer priority. You shouldn't need to modify this value. */
#define APP_BLE_CONN_CFG_TAG             1                                              /**< A tag identifying the SoftDevice BLE configuration. */

#define BATTERY_LEVEL_MEAS_INTERVAL      APP_TIMER_TICKS(2000)                          /**< Battery level measurement interval (ticks). */
#define MIN_BATTERY_LEVEL                81                                             /**< Minimum simulated battery level. */
#define MAX_BATTERY_LEVEL                100                                            /**< Maximum simulated battery level. */
#define BATTERY_LEVEL_INCREMENT          1                                              /**< Increment between each simulated battery level measurement. */

#define PNP_ID_VENDOR_ID_SOURCE          0x02                                           /**< Vendor ID Source. */
#define PNP_ID_VENDOR_ID                 0x1915                                         /**< Vendor ID. */
#define PNP_ID_PRODUCT_ID                0xEEEE                                         /**< Product ID. */
#define PNP_ID_PRODUCT_VERSION           0x0001                                         /**< Product Version. */

#define APP_ADV_FAST_INTERVAL            0x0028                                         /**< Fast advertising interval (in units of 0.625 ms. This value corresponds to 25 ms.). */
#define APP_ADV_SLOW_INTERVAL            0x0C80                                         /**< Slow advertising interval (in units of 0.625 ms. This value corrsponds to 2 seconds). */
#define APP_ADV_FAST_DURATION        3000                                           /**< The advertising duration of fast advertising in units of 10 milliseconds. */
#define APP_ADV_SLOW_DURATION        18000                                          /**< The advertising duration of slow advertising in units of 10 milliseconds. */

/*lint -emacro(524, MIN_CONN_INTERVAL) // Loss of precision */
#define MIN_CONN_INTERVAL                MSEC_TO_UNITS(7.5, UNIT_1_25_MS)               /**< Minimum connection interval (7.5 ms) */
#define MAX_CONN_INTERVAL                MSEC_TO_UNITS(30, UNIT_1_25_MS)                /**< Maximum connection interval (30 ms). */
#define SLAVE_LATENCY                    6                                              /**< Slave latency. */
#define CONN_SUP_TIMEOUT                 MSEC_TO_UNITS(430, UNIT_10_MS)                 /**< Connection supervisory timeout (430 ms). */

#define FIRST_CONN_PARAMS_UPDATE_DELAY   APP_TIMER_TICKS(5000)                          /**< Time from initiating event (connect or start of notification) to first time sd_ble_gap_conn_param_update is called (5 seconds). */
#define NEXT_CONN_PARAMS_UPDATE_DELAY    APP_TIMER_TICKS(30000)                         /**< Time between each call to sd_ble_gap_conn_param_update after the first call (30 seconds). */
#define MAX_CONN_PARAMS_UPDATE_COUNT     3                                              /**< Number of attempts before giving up the connection parameter negotiation. */

#define OUTPUT_REPORT_INDEX              0                                              /**< Index of Output Report. */
#define OUTPUT_REPORT_MAX_LEN            1                                              /**< Maximum length of Output Report. */
#define INPUT_REPORT_KEYS_INDEX          0                                              /**< Index of Input Report. */
#define OUTPUT_REPORT_BIT_MASK_CAPS_LOCK 0x02                                           /**< CAPS LOCK bit in Output Report (based on 'LED Page (0x08)' of the Universal Serial Bus HID Usage Tables). */
#define INPUT_REP_REF_ID                 0                                              /**< Id of reference to Keyboard Input Report. */
#define OUTPUT_REP_REF_ID                0                                              /**< Id of reference to Keyboard Output Report. */
#define FEATURE_REP_REF_ID               0                                              /**< ID of reference to Keyboard Feature Report. */
#define FEATURE_REPORT_MAX_LEN           2                                              /**< Maximum length of Feature Report. */
#define FEATURE_REPORT_INDEX             0                                              /**< Index of Feature Report. */

#define MAX_BUFFER_ENTRIES              5                                               /**< Number of elements that can be enqueued */

#define BASE_USB_HID_SPEC_VERSION       0x0101                                          /**< Version number of base USB HID Specification implemented by this application. */

#define INPUT_REPORT_KEYS_MAX_LEN       8                                               /**< Maximum length of the Input Report characteristic. */

#define DEAD_BEEF                       0xDEADBEEF                                      /**< Value used as error code on stack dump, can be used to identify stack location on stack unwind. */

#define SCHED_MAX_EVENT_DATA_SIZE       APP_TIMER_SCHED_EVENT_DATA_SIZE                 /**< Maximum size of scheduler events. */
#define SCHED_QUEUE_SIZE                10                                              /**< Maximum number of events in the scheduler queue. */

#define SHIFT_BUTTON_ID                 1                                               /**< Button used as 'SHIFT' Key. */
#define MODIFIER_KEY_POS                0                                               /**< Position of the modifier byte in the Input Report. */
#define SCAN_CODE_POS                   2                                               /**< This macro indicates the start position of the key scan code in a HID Report. */
#define SHIFT_KEY_CODE                  0x02                                            /**< Key code indicating the press of the Shift Key. */

#define MAX_KEYS_IN_ONE_REPORT          (INPUT_REPORT_KEYS_MAX_LEN - SCAN_CODE_POS)     /**< Maximum number of key presses that can be sent in one Input Report. */

#ifndef NFC_PAIRING_MODE
    #define NFC_PAIRING_MODE NFC_PAIRING_MODE_JUST_WORKS
#endif

/**Buffer queue access macros
 *
 * @{ */
/** Initialization of buffer list */
#define BUFFER_LIST_INIT()                                                                        \
        do                                                                                        \
        {                                                                                         \
            buffer_list.rp = 0;                                                                   \
            buffer_list.wp = 0;                                                                   \
            buffer_list.count = 0;                                                                \
        } while (0)

/** Provide status of data list is full or not */
#define BUFFER_LIST_FULL()\
        ((MAX_BUFFER_ENTRIES == buffer_list.count - 1) ? true : false)

/** Provides status of buffer list is empty or not */
#define BUFFER_LIST_EMPTY()\
        ((0 == buffer_list.count) ? true : false)

#define BUFFER_ELEMENT_INIT(i)\
        do                                                                                        \
        {                                                                                         \
            buffer_list.buffer[(i)].p_data = NULL;                                                \
        } while (0)

/** @} */

/** Abstracts buffer element */
typedef struct hid_key_buffer
{
    uint8_t    data_offset;   /**< Max Data that can be buffered for all entries */
    uint8_t    data_len;      /**< Total length of data */
    uint8_t    * p_data;      /**< Scanned key pattern */
    ble_hids_t * p_instance;  /**< Identifies peer and service instance */
} buffer_entry_t;

STATIC_ASSERT(sizeof(buffer_entry_t) % 4 == 0);

/** Circular buffer list */
typedef struct
{
    buffer_entry_t buffer[MAX_BUFFER_ENTRIES]; /**< Maximum number of entries that can enqueued in the list */
    uint8_t        rp;                         /**< Index to the read location */
    uint8_t        wp;                         /**< Index to write location */
    uint8_t        count;                      /**< Number of elements in the list */
} buffer_list_t;

STATIC_ASSERT(sizeof(buffer_list_t) % 4 == 0);

APP_TIMER_DEF(m_battery_timer_id);                                          /**< Battery timer. */
BLE_HIDS_DEF(m_hids,                                                        /**< Structure used to identify the HID service. */
             NRF_SDH_BLE_TOTAL_LINK_COUNT,
             INPUT_REPORT_KEYS_MAX_LEN,
             OUTPUT_REPORT_MAX_LEN,
             FEATURE_REPORT_MAX_LEN);
BLE_BAS_DEF(m_bas);                                                         /**< Structure used to identify the battery service. */
NRF_BLE_GATT_DEF(m_gatt);                                                   /**< GATT module instance. */
NRF_BLE_QWR_DEF(m_qwr);                                                     /**< Context for the Queued Write module.*/
BLE_ADVERTISING_DEF(m_advertising);                                         /**< Advertising module instance. */

static ble_advdata_t m_advdata;                                             /**< Struct containing advertising data */
static uint16_t      m_conn_handle  = BLE_CONN_HANDLE_INVALID;              /**< Handle of the current connection. */
static pm_peer_id_t  m_peer_id;                                             /**< Device reference handle to the current bonded central. */
static pm_peer_id_t  m_whitelist_peers[BLE_GAP_WHITELIST_ADDR_MAX_COUNT];   /**< List of peers currently in the whitelist. */
static uint32_t      m_whitelist_peer_cnt;                                  /**< Number of peers currently in the whitelist. */
static bool          m_in_boot_mode = false;                                /**< Current protocol mode. */
static bool          m_caps_on = false;                                     /**< Variable to indicate if Caps Lock is turned on. */

static sensorsim_cfg_t   m_battery_sim_cfg;                                 /**< Battery Level sensor simulator configuration. */
static sensorsim_state_t m_battery_sim_state;                               /**< Battery Level sensor simulator state. */

static ble_uuid_t m_adv_uuids[] =
{
    {BLE_UUID_HUMAN_INTERFACE_DEVICE_SERVICE, BLE_UUID_TYPE_BLE}
};

/** List to enqueue not just data to be sent, but also related information like the handle, connection handle etc */
static buffer_list_t buffer_list;

static uint8_t m_sample_key_press_scan_str[] =  /**< Key pattern to be sent when the key press button has been pushed. */
{
    0x0b, /* Key h */
    0x08, /* Key e */
    0x0f, /* Key l */
    0x0f, /* Key l */
    0x12, /* Key o */
    0x28  /* Key Return */
};

static uint8_t m_caps_on_key_scan_str[] =       /**< Key pattern to be sent when the output report has been written with the CAPS LOCK bit set. */
{
    0x06, /* Key C */
    0x04, /* Key a */
    0x13, /* Key p */
    0x16, /* Key s */
    0x12, /* Key o */
    0x11, /* Key n */
};

static uint8_t m_caps_off_key_scan_str[] =      /**< Key pattern to be sent when the output report has been written with the CAPS LOCK bit cleared. */
{
    0x06, /* Key C */
    0x04, /* Key a */
    0x13, /* Key p */
    0x16, /* Key s */
    0x12, /* Key o */
    0x09, /* Key f */
};


static void on_hids_evt(ble_hids_t * p_hids, ble_hids_evt_t * p_evt);


/**@brief Callback function for asserts in the SoftDevice.
 *
 * @details This function will be called in case of an assert in the SoftDevice.
 *
 * @warning This handler is an example only and does not fit a final product. You need to analyze
 *          how your product is supposed to react in case of Assert.
 * @warning On assert from the SoftDevice, the system can only recover on reset.
 *
 * @param[in]   line_num   Line number of the failing ASSERT call.
 * @param[in]   file_name  File name of the failing ASSERT call.
 */
void assert_nrf_callback(uint16_t line_num, const uint8_t * p_file_name)
{
    app_error_handler(DEAD_BEEF, line_num, p_file_name);
}


/**@brief Function for handling Service errors.
 *
 * @details A pointer to this function will be passed to each service which may need to inform the
 *          application about an error.
 *
 * @param[in]   nrf_error   Error code containing information about what went wrong.
 */
static void service_error_handler(uint32_t nrf_error)
{
    APP_ERROR_HANDLER(nrf_error);
}


/**@brief Function for handling advertising errors.
 *
 * @param[in] nrf_error  Error code containing information about what went wrong.
 */
static void ble_advertising_error_handler(uint32_t nrf_error)
{
    APP_ERROR_HANDLER(nrf_error);
}


/**@brief Function for performing a battery measurement, and update the Battery Level characteristic in the Battery Service.
 */
static void battery_level_update(void)
{
    ret_code_t err_code;
    uint8_t  battery_level;

    battery_level = (uint8_t)sensorsim_measure(&m_battery_sim_state, &m_battery_sim_cfg);

    err_code = ble_bas_battery_level_update(&m_bas, battery_level, BLE_CONN_HANDLE_ALL);
    if ((err_code != NRF_SUCCESS) &&
        (err_code != NRF_ERROR_INVALID_STATE) &&
        (err_code != NRF_ERROR_RESOURCES) &&
        (err_code != NRF_ERROR_BUSY) &&
        (err_code != NRF_ERROR_FORBIDDEN) &&
        (err_code != BLE_ERROR_GATTS_SYS_ATTR_MISSING)
       )
    {
        APP_ERROR_HANDLER(err_code);
    }
}


/**@brief Function for handling the Battery measurement timer timeout.
 *
 * @details This function will be called each time the battery level measurement timer expires.
 *
 * @param[in]   p_context   Pointer used for passing some arbitrary information (context) from the
 *                          app_start_timer() call to the timeout handler.
 */
static void battery_level_meas_timeout_handler(void * p_context)
{
    UNUSED_PARAMETER(p_context);
    battery_level_update();
}

/**@brief Function for the Timer initialization.
 *
 * @details Initializes the timer module.
 */
static void timers_init(void)
{
    ret_code_t err_code;

    err_code = app_timer_init();
    APP_ERROR_CHECK(err_code);

    // Create battery timer.
    err_code = app_timer_create(&m_battery_timer_id,
                                APP_TIMER_MODE_REPEATED,
                                battery_level_meas_timeout_handler);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for the GAP initialization.
 *
 * @details This function sets up all the necessary GAP (Generic Access Profile) parameters of the
 *          device including the device name, appearance, and the preferred connection parameters.
 */
static void gap_params_init(void)
{
    ret_code_t              err_code;
    ble_gap_conn_params_t   gap_conn_params;
    ble_gap_conn_sec_mode_t sec_mode;

    BLE_GAP_CONN_SEC_MODE_SET_OPEN(&sec_mode);

    err_code = sd_ble_gap_device_name_set(&sec_mode,
                                          (const uint8_t *)DEVICE_NAME,
                                          strlen(DEVICE_NAME));
    APP_ERROR_CHECK(err_code);

    err_code = sd_ble_gap_appearance_set(BLE_APPEARANCE_HID_KEYBOARD);
    APP_ERROR_CHECK(err_code);

    memset(&gap_conn_params, 0, sizeof(gap_conn_params));

    gap_conn_params.min_conn_interval = MIN_CONN_INTERVAL;
    gap_conn_params.max_conn_interval = MAX_CONN_INTERVAL;
    gap_conn_params.slave_latency     = SLAVE_LATENCY;
    gap_conn_params.conn_sup_timeout  = CONN_SUP_TIMEOUT;

    err_code = sd_ble_gap_ppcp_set(&gap_conn_params);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for initializing the GATT module.
 */
static void gatt_init(void)
{
    ret_code_t err_code = nrf_ble_gatt_init(&m_gatt, NULL);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for handling Queued Write Module errors.
 *
 * @details A pointer to this function will be passed to each service which may need to inform the
 *          application about an error.
 *
 * @param[in]   nrf_error   Error code containing information about what went wrong.
 */
static void nrf_qwr_error_handler(uint32_t nrf_error)
{
    APP_ERROR_HANDLER(nrf_error);
}


/**@brief Function for initializing the Queued write module.
 */
static void qwr_init(void)
{
    ret_code_t         err_code;
    nrf_ble_qwr_init_t qwr_init_obj = {0};

    // Initialize Queued Write Module.
    qwr_init_obj.error_handler = nrf_qwr_error_handler;

    err_code = nrf_ble_qwr_init(&m_qwr, &qwr_init_obj);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for initializing Device Information Service.
 */
static void dis_init(void)
{
    ret_code_t       err_code;
    ble_dis_init_t   dis_init_obj;
    ble_dis_pnp_id_t pnp_id;

    pnp_id.vendor_id_source = PNP_ID_VENDOR_ID_SOURCE;
    pnp_id.vendor_id        = PNP_ID_VENDOR_ID;
    pnp_id.product_id       = PNP_ID_PRODUCT_ID;
    pnp_id.product_version  = PNP_ID_PRODUCT_VERSION;

    memset(&dis_init_obj, 0, sizeof(dis_init_obj));

    ble_srv_ascii_to_utf8(&dis_init_obj.manufact_name_str, MANUFACTURER_NAME);
    dis_init_obj.p_pnp_id = &pnp_id;

    dis_init_obj.dis_char_rd_sec = SEC_JUST_WORKS;

    err_code = ble_dis_init(&dis_init_obj);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for initializing Battery Service.
 */
static void bas_init(void)
{
    ret_code_t     err_code;
    ble_bas_init_t bas_init_obj;

    memset(&bas_init_obj, 0, sizeof(bas_init_obj));

    bas_init_obj.evt_handler          = NULL;
    bas_init_obj.support_notification = true;
    bas_init_obj.p_report_ref         = NULL;
    bas_init_obj.initial_batt_level   = 100;

    bas_init_obj.bl_rd_sec        = SEC_JUST_WORKS;
    bas_init_obj.bl_cccd_wr_sec   = SEC_JUST_WORKS;
    bas_init_obj.bl_report_rd_sec = SEC_JUST_WORKS;

    err_code = ble_bas_init(&m_bas, &bas_init_obj);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for initializing HID Service.
 */
static void hids_init(void)
{
    ret_code_t                    err_code;
    ble_hids_init_t               hids_init_obj;
    ble_hids_inp_rep_init_t     * p_input_report;
    ble_hids_outp_rep_init_t    * p_output_report;
    ble_hids_feature_rep_init_t * p_feature_report;
    uint8_t                       hid_info_flags;

    static ble_hids_inp_rep_init_t     input_report_array[1];
    static ble_hids_outp_rep_init_t    output_report_array[1];
    static ble_hids_feature_rep_init_t feature_report_array[1];
    static uint8_t report_map_data[] =
    {
        0x05, 0x01,                 // Usage Page (Generic Desktop)
        0x09, 0x06,                 // Usage (Keyboard)
        0xA1, 0x01,                 // Collection (Application)
        0x05, 0x07,                 //     Usage Page (Key Codes)
        0x19, 0xe0,                 //     Usage Minimum (224)
        0x29, 0xe7,                 //     Usage Maximum (231)
        0x15, 0x00,                 //     Logical Minimum (0)
        0x25, 0x01,                 //     Logical Maximum (1)
        0x75, 0x01,                 //     Report Size (1)
        0x95, 0x08,                 //     Report Count (8)
        0x81, 0x02,                 //     Input (Data, Variable, Absolute)

        0x95, 0x01,                 //     Report Count (1)
        0x75, 0x08,                 //     Report Size (8)
        0x81, 0x01,                 //     Input (Constant) reserved byte(1)

        0x95, 0x05,                 //     Report Count (5)
        0x75, 0x01,                 //     Report Size (1)
        0x05, 0x08,                 //     Usage Page (Page# for LEDs)
        0x19, 0x01,                 //     Usage Minimum (1)
        0x29, 0x05,                 //     Usage Maximum (5)
        0x91, 0x02,                 //     Output (Data, Variable, Absolute), Led report
        0x95, 0x01,                 //     Report Count (1)
        0x75, 0x03,                 //     Report Size (3)
        0x91, 0x01,                 //     Output (Data, Variable, Absolute), Led report padding

        0x95, 0x06,                 //     Report Count (6)
        0x75, 0x08,                 //     Report Size (8)
        0x15, 0x00,                 //     Logical Minimum (0)
        0x25, 0x65,                 //     Logical Maximum (101)
        0x05, 0x07,                 //     Usage Page (Key codes)
        0x19, 0x00,                 //     Usage Minimum (0)
        0x29, 0x65,                 //     Usage Maximum (101)
        0x81, 0x00,                 //     Input (Data, Array) Key array(6 bytes)

        0x09, 0x05,                 //     Usage (Vendor Defined)
        0x15, 0x00,                 //     Logical Minimum (0)
        0x26, 0xFF, 0x00,           //     Logical Maximum (255)
        0x75, 0x08,                 //     Report Size (8 bit)
        0x95, 0x02,                 //     Report Count (2)
        0xB1, 0x02,                 //     Feature (Data, Variable, Absolute)

        0xC0                        // End Collection (Application)
    };

    memset((void *)input_report_array, 0, sizeof(ble_hids_inp_rep_init_t));
    memset((void *)output_report_array, 0, sizeof(ble_hids_outp_rep_init_t));
    memset((void *)feature_report_array, 0, sizeof(ble_hids_feature_rep_init_t));

    // Initialize HID Service
    p_input_report                      = &input_report_array[INPUT_REPORT_KEYS_INDEX];
    p_input_report->max_len             = INPUT_REPORT_KEYS_MAX_LEN;
    p_input_report->rep_ref.report_id   = INPUT_REP_REF_ID;
    p_input_report->rep_ref.report_type = BLE_HIDS_REP_TYPE_INPUT;

    p_input_report->sec.cccd_wr = SEC_JUST_WORKS;
    p_input_report->sec.wr      = SEC_JUST_WORKS;
    p_input_report->sec.rd      = SEC_JUST_WORKS;

    p_output_report                      = &output_report_array[OUTPUT_REPORT_INDEX];
    p_output_report->max_len             = OUTPUT_REPORT_MAX_LEN;
    p_output_report->rep_ref.report_id   = OUTPUT_REP_REF_ID;
    p_output_report->rep_ref.report_type = BLE_HIDS_REP_TYPE_OUTPUT;

    p_output_report->sec.wr = SEC_JUST_WORKS;
    p_output_report->sec.rd = SEC_JUST_WORKS;

    p_feature_report                      = &feature_report_array[FEATURE_REPORT_INDEX];
    p_feature_report->max_len             = FEATURE_REPORT_MAX_LEN;
    p_feature_report->rep_ref.report_id   = FEATURE_REP_REF_ID;
    p_feature_report->rep_ref.report_type = BLE_HIDS_REP_TYPE_FEATURE;

    p_feature_report->sec.rd              = SEC_JUST_WORKS;
    p_feature_report->sec.wr              = SEC_JUST_WORKS;

    hid_info_flags = HID_INFO_FLAG_REMOTE_WAKE_MSK | HID_INFO_FLAG_NORMALLY_CONNECTABLE_MSK;

    memset(&hids_init_obj, 0, sizeof(hids_init_obj));

    hids_init_obj.evt_handler                    = on_hids_evt;
    hids_init_obj.error_handler                  = service_error_handler;
    hids_init_obj.is_kb                          = true;
    hids_init_obj.is_mouse                       = false;
    hids_init_obj.inp_rep_count                  = 1;
    hids_init_obj.p_inp_rep_array                = input_report_array;
    hids_init_obj.outp_rep_count                 = 1;
    hids_init_obj.p_outp_rep_array               = output_report_array;
    hids_init_obj.feature_rep_count              = 1;
    hids_init_obj.p_feature_rep_array            = feature_report_array;
    hids_init_obj.rep_map.data_len               = sizeof(report_map_data);
    hids_init_obj.rep_map.p_data                 = report_map_data;
    hids_init_obj.hid_information.bcd_hid        = BASE_USB_HID_SPEC_VERSION;
    hids_init_obj.hid_information.b_country_code = 0;
    hids_init_obj.hid_information.flags          = hid_info_flags;
    hids_init_obj.included_services_count        = 0;
    hids_init_obj.p_included_services_array      = NULL;

    hids_init_obj.rep_map.rd_sec         = SEC_JUST_WORKS;
    hids_init_obj.hid_information.rd_sec = SEC_JUST_WORKS;

    hids_init_obj.boot_kb_inp_rep_sec.cccd_wr = SEC_JUST_WORKS;
    hids_init_obj.boot_kb_inp_rep_sec.rd      = SEC_JUST_WORKS;

    hids_init_obj.boot_kb_outp_rep_sec.rd = SEC_JUST_WORKS;
    hids_init_obj.boot_kb_outp_rep_sec.wr = SEC_JUST_WORKS;

    hids_init_obj.protocol_mode_rd_sec = SEC_JUST_WORKS;
    hids_init_obj.protocol_mode_wr_sec = SEC_JUST_WORKS;
    hids_init_obj.ctrl_point_wr_sec    = SEC_JUST_WORKS;

    err_code = ble_hids_init(&m_hids, &hids_init_obj);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for initializing services that will be used by the application.
 */
static void services_init(void)
{
    qwr_init();
    dis_init();
    bas_init();
    hids_init();
}


/**@brief Function for initializing the battery sensor simulator.
 */
static void sensor_simulator_init(void)
{
    m_battery_sim_cfg.min          = MIN_BATTERY_LEVEL;
    m_battery_sim_cfg.max          = MAX_BATTERY_LEVEL;
    m_battery_sim_cfg.incr         = BATTERY_LEVEL_INCREMENT;
    m_battery_sim_cfg.start_at_max = true;

    sensorsim_init(&m_battery_sim_state, &m_battery_sim_cfg);
}


/**@brief Function for handling a Connection Parameters error.
 *
 * @param[in]   nrf_error   Error code containing information about what went wrong.
 */
static void conn_params_error_handler(uint32_t nrf_error)
{
    APP_ERROR_HANDLER(nrf_error);
}


/**@brief Function for initializing the Connection Parameters module.
 */
static void conn_params_init(void)
{
    ret_code_t             err_code;
    ble_conn_params_init_t cp_init;

    memset(&cp_init, 0, sizeof(cp_init));

    cp_init.p_conn_params                  = NULL;
    cp_init.first_conn_params_update_delay = FIRST_CONN_PARAMS_UPDATE_DELAY;
    cp_init.next_conn_params_update_delay  = NEXT_CONN_PARAMS_UPDATE_DELAY;
    cp_init.max_conn_params_update_count   = MAX_CONN_PARAMS_UPDATE_COUNT;
    cp_init.start_on_notify_cccd_handle    = BLE_GATT_HANDLE_INVALID;
    cp_init.disconnect_on_fail             = false;
    cp_init.evt_handler                    = NULL;
    cp_init.error_handler                  = conn_params_error_handler;

    err_code = ble_conn_params_init(&cp_init);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for starting timers.
 */
static void timers_start(void)
{
    ret_code_t err_code;

    err_code = app_timer_start(m_battery_timer_id, BATTERY_LEVEL_MEAS_INTERVAL, NULL);
    APP_ERROR_CHECK(err_code);
}


/**@brief   Function for transmitting a key scan Press & Release Notification.
 *
 * @warning This handler is an example only. You need to analyze how you wish to send the key
 *          release.
 *
 * @param[in]  p_instance     Identifies the service for which Key Notifications are requested.
 * @param[in]  p_key_pattern  Pointer to key pattern.
 * @param[in]  pattern_len    Length of key pattern. 0 < pattern_len < 7.
 * @param[in]  pattern_offset Offset applied to Key Pattern for transmission.
 * @param[out] actual_len     Provides actual length of Key Pattern transmitted, making buffering of
 *                            rest possible if needed.
 * @return     NRF_SUCCESS on success, NRF_ERROR_RESOURCES in case transmission could not be
 *             completed due to lack of transmission buffer or other error codes indicating reason
 *             for failure.
 *
 * @note       In case of NRF_ERROR_RESOURCES, remaining pattern that could not be transmitted
 *             can be enqueued \ref buffer_enqueue function.
 *             In case a pattern of 'cofFEe' is the p_key_pattern, with pattern_len as 6 and
 *             pattern_offset as 0, the notifications as observed on the peer side would be
 *             1>    'c', 'o', 'f', 'F', 'E', 'e'
 *             2>    -  , 'o', 'f', 'F', 'E', 'e'
 *             3>    -  ,   -, 'f', 'F', 'E', 'e'
 *             4>    -  ,   -,   -, 'F', 'E', 'e'
 *             5>    -  ,   -,   -,   -, 'E', 'e'
 *             6>    -  ,   -,   -,   -,   -, 'e'
 *             7>    -  ,   -,   -,   -,   -,  -
 *             Here, '-' refers to release, 'c' refers to the key character being transmitted.
 *             Therefore 7 notifications will be sent.
 *             In case an offset of 4 was provided, the pattern notifications sent will be from 5-7
 *             will be transmitted.
 */
static uint32_t send_key_scan_press_release(ble_hids_t *   p_hids,
                                            uint8_t *      p_key_pattern,
                                            uint16_t       pattern_len,
                                            uint16_t       pattern_offset,
                                            uint16_t *     p_actual_len)
{
    ret_code_t err_code;
    uint16_t offset;
    uint16_t data_len;
    uint8_t  data[INPUT_REPORT_KEYS_MAX_LEN];

    // HID Report Descriptor enumerates an array of size 6, the pattern hence shall not be any
    // longer than this.
    STATIC_ASSERT((INPUT_REPORT_KEYS_MAX_LEN - 2) == 6);

    ASSERT(pattern_len <= (INPUT_REPORT_KEYS_MAX_LEN - 2));

    offset   = pattern_offset;
    data_len = pattern_len;

    do
    {
        // Reset the data buffer.
        memset(data, 0, sizeof(data));

        // Copy the scan code.
        memcpy(data + SCAN_CODE_POS + offset, p_key_pattern + offset, data_len - offset);

        if (bsp_button_is_pressed(SHIFT_BUTTON_ID))
        {
            data[MODIFIER_KEY_POS] |= SHIFT_KEY_CODE;
        }

        if (!m_in_boot_mode)
        {
            err_code = ble_hids_inp_rep_send(p_hids,
                                             INPUT_REPORT_KEYS_INDEX,
                                             INPUT_REPORT_KEYS_MAX_LEN,
                                             data,
                                             m_conn_handle);
        }
        else
        {
            err_code = ble_hids_boot_kb_inp_rep_send(p_hids,
                                                     INPUT_REPORT_KEYS_MAX_LEN,
                                                     data,
                                                     m_conn_handle);
        }

        if (err_code != NRF_SUCCESS)
        {
            break;
        }

        offset++;
    } while (offset <= data_len);

    *p_actual_len = offset;

    return err_code;
}


/**@brief   Function for initializing the buffer queue used to key events that could not be
 *          transmitted
 *
 * @warning This handler is an example only. You need to analyze how you wish to buffer or buffer at
 *          all.
 *
 * @note    In case of HID keyboard, a temporary buffering could be employed to handle scenarios
 *          where encryption is not yet enabled or there was a momentary link loss or there were no
 *          Transmit buffers.
 */
static void buffer_init(void)
{
    uint32_t buffer_count;

    BUFFER_LIST_INIT();

    for (buffer_count = 0; buffer_count < MAX_BUFFER_ENTRIES; buffer_count++)
    {
        BUFFER_ELEMENT_INIT(buffer_count);
    }
}


/**@brief Function for enqueuing key scan patterns that could not be transmitted either completely
 *        or partially.
 *
 * @warning This handler is an example only. You need to analyze how you wish to send the key
 *          release.
 *
 * @param[in]  p_hids         Identifies the service for which Key Notifications are buffered.
 * @param[in]  p_key_pattern  Pointer to key pattern.
 * @param[in]  pattern_len    Length of key pattern.
 * @param[in]  offset         Offset applied to Key Pattern when requesting a transmission on
 *                            dequeue, @ref buffer_dequeue.
 * @return     NRF_SUCCESS on success, else an error code indicating reason for failure.
 */
static uint32_t buffer_enqueue(ble_hids_t *            p_hids,
                               uint8_t *               p_key_pattern,
                               uint16_t                pattern_len,
                               uint16_t                offset)
{
    buffer_entry_t * element;
    ret_code_t       err_code = NRF_SUCCESS;

    if (BUFFER_LIST_FULL())
    {
        // Element cannot be buffered.
        err_code = NRF_ERROR_NO_MEM;
    }
    else
    {
        // Make entry of buffer element and copy data.
        element                 = &buffer_list.buffer[(buffer_list.wp)];
        element->p_instance     = p_hids;
        element->p_data         = p_key_pattern;
        element->data_offset    = offset;
        element->data_len       = pattern_len;

        buffer_list.count++;
        buffer_list.wp++;

        if (buffer_list.wp == MAX_BUFFER_ENTRIES)
        {
            buffer_list.wp = 0;
        }
    }

    return err_code;
}


/**@brief   Function to dequeue key scan patterns that could not be transmitted either completely of
 *          partially.
 *
 * @warning This handler is an example only. You need to analyze how you wish to send the key
 *          release.
 *
 * @param[in]  tx_flag   Indicative of whether the dequeue should result in transmission or not.
 * @note       A typical example when all keys are dequeued with transmission is when link is
 *             disconnected.
 *
 * @return     NRF_SUCCESS on success, else an error code indicating reason for failure.
 */
static uint32_t buffer_dequeue(bool tx_flag)
{
    buffer_entry_t * p_element;
    ret_code_t       err_code = NRF_SUCCESS;
    uint16_t         actual_len;

    if (BUFFER_LIST_EMPTY())
    {
        err_code = NRF_ERROR_NOT_FOUND;
    }
    else
    {
        bool remove_element = true;

        p_element = &buffer_list.buffer[(buffer_list.rp)];

        if (tx_flag)
        {
            err_code = send_key_scan_press_release(p_element->p_instance,
                                                   p_element->p_data,
                                                   p_element->data_len,
                                                   p_element->data_offset,
                                                   &actual_len);
            // An additional notification is needed for release of all keys, therefore check
            // is for actual_len <= element->data_len and not actual_len < element->data_len
            if ((err_code == NRF_ERROR_RESOURCES) && (actual_len <= p_element->data_len))
            {
                // Transmission could not be completed, do not remove the entry, adjust next data to
                // be transmitted
                p_element->data_offset = actual_len;
                remove_element         = false;
            }
        }

        if (remove_element)
        {
            BUFFER_ELEMENT_INIT(buffer_list.rp);

            buffer_list.rp++;
            buffer_list.count--;

            if (buffer_list.rp == MAX_BUFFER_ENTRIES)
            {
                buffer_list.rp = 0;
            }
        }
    }

    return err_code;
}


/**@brief Function for sending sample key presses to the peer.
 *
 * @param[in]   key_pattern_len   Pattern length.
 * @param[in]   p_key_pattern     Pattern to be sent.
 */
static void keys_send(uint8_t key_pattern_len, uint8_t * p_key_pattern)
{
    ret_code_t err_code;
    uint16_t actual_len;

    err_code = send_key_scan_press_release(&m_hids,
                                           p_key_pattern,
                                           key_pattern_len,
                                           0,
                                           &actual_len);
    // An additional notification is needed for release of all keys, therefore check
    // is for actual_len <= key_pattern_len and not actual_len < key_pattern_len.
    if ((err_code == NRF_ERROR_RESOURCES) && (actual_len <= key_pattern_len))
    {
        // Buffer enqueue routine return value is not intentionally checked.
        // Rationale: Its better to have a a few keys missing than have a system
        // reset. Recommendation is to work out most optimal value for
        // MAX_BUFFER_ENTRIES to minimize chances of buffer queue full condition
        UNUSED_VARIABLE(buffer_enqueue(&m_hids, p_key_pattern, key_pattern_len, actual_len));
    }


    if ((err_code != NRF_SUCCESS) &&
        (err_code != NRF_ERROR_INVALID_STATE) &&
        (err_code != NRF_ERROR_RESOURCES) &&
        (err_code != BLE_ERROR_GATTS_SYS_ATTR_MISSING)
    )
    {
        APP_ERROR_HANDLER(err_code);
    }
}


/**@brief Function for handling the HID Report Characteristic Write event.
 *
 * @param[in]   p_evt   HID service event.
 */
static void on_hid_rep_char_write(ble_hids_evt_t *p_evt)
{
    if (p_evt->params.char_write.char_id.rep_type == BLE_HIDS_REP_TYPE_OUTPUT)
    {
        ret_code_t err_code;
        uint8_t  report_val;
        uint8_t  report_index = p_evt->params.char_write.char_id.rep_index;

        if (report_index == OUTPUT_REPORT_INDEX)
        {
            // This code assumes that the outptu report is one byte long. Hence the following
            // static assert is made.
            STATIC_ASSERT(OUTPUT_REPORT_MAX_LEN == 1);

            err_code = ble_hids_outp_rep_get(&m_hids,
                                             report_index,
                                             OUTPUT_REPORT_MAX_LEN,
                                             0,
                                             m_conn_handle,
                                             &report_val);
            APP_ERROR_CHECK(err_code);

            if (!m_caps_on && ((report_val & OUTPUT_REPORT_BIT_MASK_CAPS_LOCK) != 0))
            {
                // Caps Lock is turned On.
                err_code = bsp_indication_set(BSP_INDICATE_ALERT_3);
                APP_ERROR_CHECK(err_code);

                keys_send(sizeof(m_caps_on_key_scan_str), m_caps_on_key_scan_str);
                m_caps_on = true;
            }
            else if (m_caps_on && ((report_val & OUTPUT_REPORT_BIT_MASK_CAPS_LOCK) == 0))
            {
                // Caps Lock is turned Off .
                err_code = bsp_indication_set(BSP_INDICATE_ALERT_OFF);
                APP_ERROR_CHECK(err_code);

                keys_send(sizeof(m_caps_off_key_scan_str), m_caps_off_key_scan_str);
                m_caps_on = false;
            }
            else
            {
                // The report received is not supported by this application. Do nothing.
            }
        }
    }
}


/**@brief Function for putting the chip into sleep mode.
 *
 * @note This function will not return.
 */
static void sleep_mode_enter(void)
{
    ret_code_t err_code;

    err_code = bsp_indication_set(BSP_INDICATE_IDLE);
    APP_ERROR_CHECK(err_code);

    // Prepare wakeup buttons.
    err_code = bsp_btn_ble_sleep_mode_prepare();
    APP_ERROR_CHECK(err_code);

    // Go to system-off mode (this function will not return; wakeup will cause a reset).
    err_code = sd_power_system_off();
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for handling HID events.
 *
 * @details This function will be called for all HID events which are passed to the application.
 *
 * @param[in]   p_hids  HID service structure.
 * @param[in]   p_evt   Event received from the HID service.
 */
static void on_hids_evt(ble_hids_t * p_hids, ble_hids_evt_t *p_evt)
{
    switch (p_evt->evt_type)
    {
        case BLE_HIDS_EVT_BOOT_MODE_ENTERED:
            m_in_boot_mode = true;
            break;//BLE_HIDS_EVT_BOOT_MODE_ENTERED

        case BLE_HIDS_EVT_REPORT_MODE_ENTERED:
            m_in_boot_mode = false;
            break;//BLE_HIDS_EVT_REPORT_MODE_ENTERED

        case BLE_HIDS_EVT_REP_CHAR_WRITE:
            on_hid_rep_char_write(p_evt);
            break;//BLE_HIDS_EVT_REP_CHAR_WRITE

        default:
            // No implementation needed.
            break;
    }
}


/**@brief Function for handling advertising events.
 *
 * @details This function will be called for advertising events which are passed to the application.
 *
 * @param[in] ble_adv_evt  Advertising event.
 */
static void on_adv_evt(ble_adv_evt_t ble_adv_evt)
{
    ret_code_t err_code;

    switch (ble_adv_evt)
    {
        case BLE_ADV_EVT_DIRECTED_HIGH_DUTY:
            NRF_LOG_INFO("Directed advertising.");
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING_DIRECTED);
            APP_ERROR_CHECK(err_code);
            break;//BLE_ADV_EVT_DIRECTED_HIGH_DUTY

        case BLE_ADV_EVT_FAST:
            NRF_LOG_INFO("Fast advertising.");
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING);
            APP_ERROR_CHECK(err_code);
            break;//BLE_ADV_EVT_FAST

        case BLE_ADV_EVT_SLOW:
            NRF_LOG_INFO("Slow advertising.");
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING_SLOW);
            APP_ERROR_CHECK(err_code);
            break;//BLE_ADV_EVT_SLOW

        case BLE_ADV_EVT_FAST_WHITELIST:
            NRF_LOG_INFO("Fast advertising with whitelist.");
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING_WHITELIST);
            APP_ERROR_CHECK(err_code);
            break;//BLE_ADV_EVT_FAST_WHITELIST

        case BLE_ADV_EVT_SLOW_WHITELIST:
            NRF_LOG_INFO("Slow advertising with whitelist.");
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING_WHITELIST);
            APP_ERROR_CHECK(err_code);
            break;//BLE_ADV_EVT_SLOW_WHITELIST

        case BLE_ADV_EVT_IDLE:
            NRF_LOG_INFO("Advertising stopped.");
            err_code = bsp_indication_set(BSP_INDICATE_IDLE);
            APP_ERROR_CHECK(err_code);
            sleep_mode_enter();
            break;//BLE_ADV_EVT_IDLE

        case BLE_ADV_EVT_WHITELIST_REQUEST:
        {
            ble_gap_addr_t whitelist_addrs[BLE_GAP_WHITELIST_ADDR_MAX_COUNT];
            ble_gap_irk_t  whitelist_irks[BLE_GAP_WHITELIST_ADDR_MAX_COUNT];
            uint32_t       addr_cnt = BLE_GAP_WHITELIST_ADDR_MAX_COUNT;
            uint32_t       irk_cnt  = BLE_GAP_WHITELIST_ADDR_MAX_COUNT;

            err_code = pm_whitelist_get(whitelist_addrs,
                                        &addr_cnt,
                                        whitelist_irks,
                                        &irk_cnt);
            APP_ERROR_CHECK(err_code);
            NRF_LOG_DEBUG("pm_whitelist_get returns %d addr in whitelist and %d irk whitelist",
                           addr_cnt,
                           irk_cnt);

            // Apply the whitelist.
            err_code = ble_advertising_whitelist_reply(&m_advertising,
                                                       whitelist_addrs,
                                                       addr_cnt,
                                                       whitelist_irks,
                                                       irk_cnt);
            APP_ERROR_CHECK(err_code);
        } break;

        case BLE_ADV_EVT_PEER_ADDR_REQUEST:
        {
            pm_peer_data_bonding_t peer_bonding_data;

            // Only Give peer address if we have a handle to the bonded peer.
            if (m_peer_id != PM_PEER_ID_INVALID)
            {
                err_code = pm_peer_data_bonding_load(m_peer_id, &peer_bonding_data);
                if (err_code != NRF_ERROR_NOT_FOUND)
                {
                    APP_ERROR_CHECK(err_code);

                    ble_gap_addr_t * p_peer_addr = &(peer_bonding_data.peer_ble_id.id_addr_info);
                    err_code = ble_advertising_peer_addr_reply(&m_advertising, p_peer_addr);
                    APP_ERROR_CHECK(err_code);
                }
            }
        } break;//BLE_ADV_EVT_PEER_ADDR_REQUEST

        default:
            // No implementation needed.
            break;
    }
}


/**@brief Function for handling BLE events.
 *
 * @param[in]   p_ble_evt   Bluetooth stack event.
 * @param[in]   p_context   Unused.
 */
static void ble_evt_handler(ble_evt_t const * p_ble_evt, void * p_context)
{
    ret_code_t err_code;

    switch (p_ble_evt->header.evt_id)
    {
        case BLE_GAP_EVT_CONNECTED:
            NRF_LOG_INFO("Connected");
            err_code = bsp_indication_set(BSP_INDICATE_CONNECTED);
            APP_ERROR_CHECK(err_code);
            m_conn_handle   = p_ble_evt->evt.gap_evt.conn_handle;
            err_code = nrf_ble_qwr_conn_handle_assign(&m_qwr, m_conn_handle);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_GAP_EVT_DISCONNECTED:
        {
            NRF_LOG_INFO("Disconnected");

            // Dequeue all keys without transmission.
            (void) buffer_dequeue(false);

            m_conn_handle  = BLE_CONN_HANDLE_INVALID;

            // Reset m_caps_on variable. Upon reconnect, the HID host will re-send the Output
            // report containing the Caps lock state.
            m_caps_on = false;

            err_code = bsp_indication_set(BSP_INDICATE_IDLE);
            APP_ERROR_CHECK(err_code);
            sleep_mode_enter();
        } break; // BLE_GAP_EVT_DISCONNECTED

        case BLE_GAP_EVT_PHY_UPDATE_REQUEST:
        {
            NRF_LOG_DEBUG("PHY update request.");
            ble_gap_phys_t const phys =
            {
                .rx_phys = BLE_GAP_PHY_AUTO,
                .tx_phys = BLE_GAP_PHY_AUTO,
            };
            err_code = sd_ble_gap_phy_update(p_ble_evt->evt.gap_evt.conn_handle, &phys);
            APP_ERROR_CHECK(err_code);
        } break;

        case BLE_GATTS_EVT_HVN_TX_COMPLETE:
            // Send next key event
            (void) buffer_dequeue(true);
            break;

        case BLE_GATTC_EVT_TIMEOUT:
            // Disconnect on GATT Client timeout event.
            NRF_LOG_DEBUG("GATT Client Timeout.");
            err_code = sd_ble_gap_disconnect(p_ble_evt->evt.gattc_evt.conn_handle,
                                             BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_GATTS_EVT_TIMEOUT:
            // Disconnect on GATT Server timeout event.
            NRF_LOG_DEBUG("GATT Server Timeout.");
            err_code = sd_ble_gap_disconnect(p_ble_evt->evt.gatts_evt.conn_handle,
                                             BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_GAP_EVT_CONN_SEC_UPDATE:
            NRF_LOG_INFO("BLE_GAP_EVT_CONN_SEC_UPDATE");
            NRF_LOG_INFO("Security mode: %u. Security level: %u",
                         p_ble_evt->evt.gap_evt.params.conn_sec_update.conn_sec.sec_mode.sm,
                         p_ble_evt->evt.gap_evt.params.conn_sec_update.conn_sec.sec_mode.lv);
            break;

        default:
            // No implementation needed.
            break;
    }
}


/**@brief Function for initializing the BLE stack.
 *
 * @details Initializes the SoftDevice and the BLE event interrupt.
 */
static void ble_stack_init(void)
{
    ret_code_t err_code;

    err_code = nrf_sdh_enable_request();
    APP_ERROR_CHECK(err_code);

    // Configure the BLE stack using the default settings.
    // Fetch the start address of the application RAM.
    uint32_t ram_start = 0;
    err_code = nrf_sdh_ble_default_cfg_set(APP_BLE_CONN_CFG_TAG, &ram_start);
    APP_ERROR_CHECK(err_code);

    // Enable BLE stack.
    err_code = nrf_sdh_ble_enable(&ram_start);
    APP_ERROR_CHECK(err_code);

    // Register a handler for BLE events.
    NRF_SDH_BLE_OBSERVER(m_ble_observer, APP_BLE_OBSERVER_PRIO, ble_evt_handler, NULL);
}


/**@brief Function for the Event Scheduler initialization.
 */
static void scheduler_init(void)
{
    APP_SCHED_INIT(SCHED_MAX_EVENT_DATA_SIZE, SCHED_QUEUE_SIZE);
}


/**@brief Function for handling events from the BSP module.
 *
 * @param[in]   event   Event generated by button press.
 */
static void bsp_event_handler(bsp_event_t event)
{
    static uint8_t * p_key = m_sample_key_press_scan_str;
    static uint8_t   size  = 0;

    ret_code_t err_code;

    switch (event)
    {
        case BSP_EVENT_SLEEP:
            sleep_mode_enter();
            break;

        case BSP_EVENT_DISCONNECT:
            err_code = sd_ble_gap_disconnect(m_conn_handle, BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
            if (err_code != NRF_ERROR_INVALID_STATE)
            {
                APP_ERROR_CHECK(err_code);
            }
            break;

        case BSP_EVENT_WHITELIST_OFF:
            if (m_conn_handle == BLE_CONN_HANDLE_INVALID)
            {
                err_code = ble_advertising_restart_without_whitelist(&m_advertising);
                if (err_code != NRF_ERROR_INVALID_STATE)
                {
                    APP_ERROR_CHECK(err_code);
                }
            }
            break;

        case BSP_EVENT_KEY_0:
            if (m_conn_handle != BLE_CONN_HANDLE_INVALID)
            {
                keys_send(1, p_key);
                p_key++;
                size++;
                if (size == MAX_KEYS_IN_ONE_REPORT)
                {
                    p_key = m_sample_key_press_scan_str;
                    size = 0;
                }
            }
            break;

        default:
            // No implementation needed.
            break;
    }
}


/**@brief Function for handling Peer Manager events.
 *
 * @param[in] p_evt  Peer Manager event.
 */
static void pm_evt_handler(pm_evt_t const * p_evt)
{
    ret_code_t err_code;

    pm_handler_on_pm_evt(p_evt);
    pm_handler_flash_clean(p_evt);

    switch (p_evt->evt_id)
    {
        case PM_EVT_CONN_SEC_SUCCEEDED:
            m_peer_id = p_evt->peer_id;
            break;

        case PM_EVT_CONN_SEC_PARAMS_REQ:
            // Send event to the NFC BLE pairing library as it may dynamically alternate
            // security parameters to achieve highest possible security level.
            err_code = nfc_ble_pair_on_pm_params_req(p_evt);
            APP_ERROR_CHECK(err_code);
            break;

        case PM_EVT_PEER_DATA_UPDATE_SUCCEEDED:
            // Note: You should check on what kind of white list policy your application should use.
            if (     p_evt->params.peer_data_update_succeeded.flash_changed
                 && (p_evt->params.peer_data_update_succeeded.data_id == PM_PEER_DATA_ID_BONDING))
            {
                NRF_LOG_DEBUG("New Bond, add the peer to the whitelist if possible");
                NRF_LOG_DEBUG("\tm_whitelist_peer_cnt %d, MAX_PEERS_WLIST %d",
                               m_whitelist_peer_cnt + 1,
                               BLE_GAP_WHITELIST_ADDR_MAX_COUNT);

                if (m_whitelist_peer_cnt < BLE_GAP_WHITELIST_ADDR_MAX_COUNT)
                {
                    // Bonded to a new peer, add it to the whitelist.
                    m_whitelist_peers[m_whitelist_peer_cnt++] = m_peer_id;

                    // The whitelist has been modified, update it in the Peer Manager.
                    err_code = pm_device_identities_list_set(m_whitelist_peers, m_whitelist_peer_cnt);
                    if (err_code != NRF_ERROR_NOT_SUPPORTED)
                    {
                        APP_ERROR_CHECK(err_code);
                    }

                    err_code = pm_whitelist_set(m_whitelist_peers, m_whitelist_peer_cnt);
                    APP_ERROR_CHECK(err_code);
                }
            }
            break;

        default:
            break;
    }
}


/**@brief Function for the Peer Manager initialization.
 *
 * @param[in] erase_bonds  Indicates whether bonding information should be cleared from
 *                         persistent storage during initialization of the Peer Manager.
 */
static void peer_manager_init(bool erase_bonds)
{
    ret_code_t err_code;

    err_code = pm_init();
    APP_ERROR_CHECK(err_code);

    if (erase_bonds)
    {
        err_code = pm_peers_delete();
        APP_ERROR_CHECK(err_code);
    }

    err_code = pm_register(pm_evt_handler);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for initializing buttons and LEDs.
 *
 * @param[out] p_erase_bonds  Will be true if the clear bonding button was pressed to wake the application up.
 */
static void buttons_leds_init(bool * p_erase_bonds, bool * p_wake_on_button)
{
    bsp_event_t startup_event;

    ret_code_t err_code = bsp_init(BSP_INIT_LEDS | BSP_INIT_BUTTONS, bsp_event_handler);
    APP_ERROR_CHECK(err_code);

    err_code = bsp_btn_ble_init(NULL, &startup_event);
    APP_ERROR_CHECK(err_code);

    *p_erase_bonds    = (startup_event == BSP_EVENT_CLEAR_BONDING_DATA);
    *p_wake_on_button = (startup_event == BSP_EVENT_WAKEUP);
}


/**@brief Fetch the list of peer manager peer IDs.
 *
 * @param[inout] p_peers   The buffer where to store the list of peer IDs.
 * @param[inout] p_size    In: The size of the @p p_peers buffer.
 *                         Out: The number of peers copied in the buffer.
 */
static void peer_list_get(pm_peer_id_t * p_peers, uint32_t * p_size)
{
    pm_peer_id_t peer_id;
    uint32_t     peers_to_copy;

    peers_to_copy = (*p_size < BLE_GAP_WHITELIST_ADDR_MAX_COUNT) ?
                     *p_size : BLE_GAP_WHITELIST_ADDR_MAX_COUNT;

    peer_id = pm_next_peer_id_get(PM_PEER_ID_INVALID);
    *p_size = 0;

    while ((peer_id != PM_PEER_ID_INVALID) && (peers_to_copy--))
    {
        p_peers[(*p_size)++] = peer_id;
        peer_id = pm_next_peer_id_get(peer_id);
    }
}


static void whitelist_load(void)
{
    ret_code_t ret;

    memset(m_whitelist_peers, PM_PEER_ID_INVALID, sizeof(m_whitelist_peers));
    m_whitelist_peer_cnt = (sizeof(m_whitelist_peers) / sizeof(pm_peer_id_t));

    peer_list_get(m_whitelist_peers, &m_whitelist_peer_cnt);

    // Setup the device identies list.
    // Some SoftDevices do not support this feature.
    ret = pm_device_identities_list_set(m_whitelist_peers, m_whitelist_peer_cnt);
    if (ret != NRF_ERROR_NOT_SUPPORTED)
    {
        APP_ERROR_CHECK(ret);
    }

    ret = pm_whitelist_set(m_whitelist_peers, m_whitelist_peer_cnt);
    APP_ERROR_CHECK(ret);
}


/**@brief Function for initializing the Advertising functionality.
 */
static void advertising_init(void)
{
    uint32_t               err_code;
    ble_advertising_init_t init;

    memset(&init, 0, sizeof(init));

    //Only set up adv_data. Options will be set depending on if advertising will be enabled or not.
    m_advdata.name_type               = BLE_ADVDATA_FULL_NAME;
    m_advdata.include_appearance      = true;
    m_advdata.flags                   = BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE;
    m_advdata.uuids_complete.uuid_cnt = sizeof(m_adv_uuids) / sizeof(m_adv_uuids[0]);
    m_advdata.uuids_complete.p_uuids  = m_adv_uuids;

    init.advdata = m_advdata;

    init.config.ble_adv_whitelist_enabled          = true;
    init.config.ble_adv_directed_high_duty_enabled = true;
    init.config.ble_adv_directed_enabled           = false;
    init.config.ble_adv_directed_interval          = 0;
    init.config.ble_adv_directed_timeout           = 0;
    init.config.ble_adv_fast_enabled               = true;
    init.config.ble_adv_fast_interval              = APP_ADV_FAST_INTERVAL;
    init.config.ble_adv_fast_timeout               = APP_ADV_FAST_DURATION;
    init.config.ble_adv_slow_enabled               = true;
    init.config.ble_adv_slow_interval              = APP_ADV_SLOW_INTERVAL;
    init.config.ble_adv_slow_timeout               = APP_ADV_SLOW_DURATION;
    init.config.ble_adv_on_disconnect_disabled     = true;

    init.evt_handler   = on_adv_evt;
    init.error_handler = ble_advertising_error_handler;

    err_code = ble_advertising_init(&m_advertising, &init);
    APP_ERROR_CHECK(err_code);

    ble_advertising_conn_cfg_tag_set(&m_advertising, APP_BLE_CONN_CFG_TAG);
}


/**@brief Function for initializing power management.
 */
static void power_management_init(void)
{
    ret_code_t err_code;
    err_code = nrf_pwr_mgmt_init();
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for handling the idle state (main loop).
 *
 * @details If there is no pending log operation, then sleep until next the next event occurs.
 */
static void idle_state_handle(void)
{
    ret_code_t err_code;

    err_code = nrf_ble_lesc_request_handler();
    if (err_code != NRF_ERROR_INVALID_STATE)
    {
        APP_ERROR_CHECK(err_code);
    }

    app_sched_execute();
    if (NRF_LOG_PROCESS() == false)
    {
        nrf_pwr_mgmt_run();
    }
}


/**@brief Function for initializing nrf logger.
 */
static void logs_init()
{
    ret_code_t err_code = NRF_LOG_INIT(NULL);
    APP_ERROR_CHECK(err_code);

    NRF_LOG_DEFAULT_BACKENDS_INIT();
}


/**@brief Function for initializing NFC BLE pairing module.
 */
static void nfc_pairing_init()
{
    ret_code_t err_code = nfc_ble_pair_init(&m_advertising, (nfc_pairing_mode_t)NFC_PAIRING_MODE);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for application main entry.
 */
int main(void)
{
    bool erase_bonds;
    bool wake_on_button;

    // Initialize.
    logs_init();
    timers_init();
    buttons_leds_init(&erase_bonds, &wake_on_button);
    power_management_init();
    ble_stack_init();
    scheduler_init();
    peer_manager_init(erase_bonds);
    if (erase_bonds == true)
    {
        NRF_LOG_INFO("Bonds erased!");
    }
    gap_params_init();
    gatt_init();
    whitelist_load();
    advertising_init();
    nfc_pairing_init();
    services_init();
    sensor_simulator_init();
    conn_params_init();
    buffer_init();

    // Start execution..
    NRF_LOG_INFO("HID Keyboard NFC started.");
    timers_start();

    // Enter main loop.
    for (;;)
    {
        idle_state_handle();
    }
}

/**
 * @}
 */
